I learned it recently and it's actually pretty easy to pick up. If you have 10 minutes to spare, you can watch
this video (I think it's from the actual game designer). But this is how it goes, in short:
You are part of the Resistance, trying to overthrow the monarchy (or something).
Imperial spies have infiltrated your ranks.
A leader is randomly selected at the start and the position rotates after that. The leader proposes a group of people to go on a mission.
Everyone votes whether or not to let the team go. If the vote fails, the next leader steps up to propose a new team.
When a mission is approved, the people selected vote in secret as to whether the mission succeeds or fails. Resistance Officers must vote yes (no sabotaging yourself just to troll people). Spies may choose to fail the mission.
If three missions succeed, the Resistance wins. If three missions fail, the Spies win.
Things I like about it over Mafia:
- There is concrete information. If a mission fails, you know at least one person on that mission was a spy.
- People are not lynched. Also, even if you are discovered as a spy, you can continue to influence events in many ways.